1. Field of the invention
The present invention concerns automatic mail handling. It relates specifically to an envelope flap folding device for closing filled envelopes.
2. Description of the prior art
A device of this kind may form part of an inserter machine into which it is integrated. In this case the inserter machine is supplied with separate enclosures from a folding device and empty envelopes from an envelope unstacker. It incorporates a device for transferring empty envelopes to an insertion station where they are held open, a device for transferring the enclosures and inserting them into the successive envelopes presented to the insertion station (a transfer and insertion carriage, for example), a device for ejecting filled but still open envelopes and a device for folding down the flap of the ejected envelopes.
As an alternative to this a device of this kind may be semi-independent of any inserter machine and simply coupled to the output from the device for ejecting filled envelopes which feeds it or totally independent of an inserter machine and coupled to an envelope unstacker taking envelopes one by one from a magazine in which they are stored filled and with their flap wide open.
As a general rule the flaps of envelopes presented open are folded down as they move along a guide path. After the flaps are folded down the guide path can in turn feed a subsequent processing device such as a franking machine or a stacker.
U.S. Pat. No. 3 811 407 describes a device of this kind designed to feed a franking machine. In the embodiment described in this document the open envelopes are received separately on a platform which constitutes the envelope guide path. The body of the received envelopes rests on and is fed along the upper surface of the platform whereas the flap projects beyond one edge of the platform and hangs freely. A first deflector member guides the flap and applies it against a moistening member mounted under the platform and comprising a wick supplied from a water reservoir into which it dips. This first deflector member has a complex shape in order to guide the flap and press its gummed region firmly against the wick. It extends beyond the moistening member and/or is associated with a second deflector member to guide the moistened flap above the platform through an opening in the platform where a pressure plate then stick it to the body of the envelope, in order to feed the latter to the franking machine.
This known device is large and its structure is relatively complex. The device has the disadvantage of relating the flap folding operation to the moistening operation so that at the end of folding the flap is fixed in a definitive way to the body of the envelope. It is therefore not suitable for automatic handling of mail that can be sent sealed or unsealed, unsealed mail being sendable at reduced cost.
An object of the present invention is to provide an envelope flap folding device avoiding these disadvantages.